The goal of this study is to examine the effects of prolactin and adenosine on human and rat granulosa cells during follicular development. Preliminary evidence indicates that granulosa cells from rats treated with prolactin in vivo during follicular development show an increased acute response to follicle stimulating hormone (FSH) with cyclic-AMP accumulation. In addition, adenosine not only augments FSH response directly, but also potentiates the FSH response to prolactin. In light of these observations, the specific aims of this study are two-fold: first, to more fully describe and document the cellular effects of prolactin and of adenosine on FSH response, and second, to investigate the cellular mechanisms by which these effects occur. Cultured rat and human granulosa cells will be examined in the presence of FSH with both prolactin and adenosine in vitro to determine individual and/or additive effects on the stimulation of cyclic-AMP and estradiol production. The mechanism of adenosine and prolactin effects will be investigated. An intra- vs. extra-cellular site of adenosine action will be examined using adenosine analogs and the effect of prolactin on FSH and luteinizing hormone (LH) receptors will be evaluated in membrane binding studies using iodinated gonadotropins. Requisites for adequate corpus luteum function include, but may not be limited to, properly modulated gonadotropin stimulation both by FSH during follicular growth and by LH at the time of ovulation. Appropriate response to these stimuli is indicated by sufficient progesterone production during the luteal phase. Prolactin and adenosine may be important physiologic modulators of adequate folliculogenesis and thus luteal function. This study is designed to examine the effects of prolactin and adenosine, both separately and together, on cyclic-AMP and steroid production in human and rat granulosa cells. These results may lead to a better understanding of the pathophysiology resulting in abnormal ovarian function in the presence of elevated levels of prolactin; a situation which has important clinical correlates in human disease.